This Program Project is using in vitro model systems to investigate the mechanisms by which environmental chemicals interact with cells, alone and in combination, and the mechanisms by which the cells respond to exposure to environmental chemicals. The objectives are to (a) determine the role of different pathways of hydrocarbon metabolism in the induction of biological effects; (b) test the hypothesis that various types of inducers of aryl hydrocarbon hydroxylase (AHH) share specific but common binding sites and a common pathway leading to the induction of the enzyme; (c) determine the role of altered regulation of polyamine biosynthesis in malignant transformation and tumor promotion; (4) study the effects of chemical carcinogens and tumor promoters on vascular endothelial cells; and (5) identify genetic information with the induction and expression of chemically-induced tumors.